body {
    /* background: #f2f2f2; */
    background: #282c34;
}

.frame {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 400px;
    height: 400px;
    margin-top: -200px;
    margin-left: -200px;
    border-radius: 2px;
    box-shadow: 1px 2px 10px 0px rgba(0, 0, 0, 0.25);
    overflow: hidden;
    background: #9b59b6;
    color: #fff;
}

.wave {
    position: absolute;
    height: 2px;
    width: 400px;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);

    .dot {
        float: left;
        width: 2px;
        height: 2px;
        border-radius: 1px;
        background: #fff;

        animation: move 3s ease-in-out infinite;

        --offset: calc(var(--i) * var(--i) / 70 * 1px);

        &:nth-child(n + 100) {
            --offset: calc((200 - var(--i)) * (200 - var(--i)) / 70 * 1px);
        }
    }
}

@keyframes move {
    0%,
    100% {
        transform: translateY(var(--offset));
    }
    50% {
        transform: translateY(calc(var(--offset) * -1));
    }
}
